Lithographing process.



UNITED STATES PATENT ()FFICE.

JOSEPH JAMES, OF BALTIMORE, IVJIARYLAND.

mrnoennrnme r'nocnss.

No Drawing.

modern methods of printing, lithographing more recently has to a very large extent been done on metal, in that with metal plates lithographic printing may be done on the modern cylinder or rotary presses.

The primary object of the invention is to improve the production of metallic lithographic plates with a View to the preservation of the life of the plates whereby a greater number of impressions may be made from a single plate than has heretofore been possible.

A further object accomplished by my invention is to so prepare metallic lithographic plates that better results may be attained in printing with the plates and better work and more clearly brought out lines will be the result of their use.

My improved process begins after the transferman finishes the plate by the known process now in universal use which known process will now be briefly described.

The metal plate is placed with its grain side up, which side is sensitive to grease. The transfer man now makes an impression from the original stone or plate by means of a paper surfaced with a suitable material to produce an impression and this impression is placed on the grainy surface of the plate and subjected to pressure. The paper is then soaked off the plate with water, leaving the ink on the plate which is now prepared for etching by giving it a coating of a solution of gum arabic, and drying, and rubbing ink upon it to its full capacity, and dusting with talcum powder. The etching is now done with a solution of phosphoric acid and gum arabic. The plate is again coated with the gum arabic solution and dried, after which the ink is washed off with turpentine and the plate is given a coat of asphaltum dissolved in turpentine and tested. At this point my improved process Specification of Letters Batentl is ready for use.

PatentedNov. 30, 1915.

Application filedMarch 8, 1915. Serial No. 12,854.

departs from the old and well known methods as follows: The plate being thus etched, gummed and dried, is then washed out withturpentine and given, with a soft rag, sponge or brush, an even coat of banana oil,'or neutralized stearic acid for the purpose of rendering the work on the plate impervious to the acids used in the etching and subsequent cleaning of the plate during the process of printlng, after whlch it is again reetched to any desired extent for the purpose of removing any remaining grease or foreign matter from the non-printing surface of the plate, when it is ready for the press. If, after a number of impressions have been made, the plate should not ink up freely, 'it should be again coated with the gum arabic solution, washed with turpentine and banana oil applied as before, when it should again be etched, these operations being repeated, if found necessary, until the destruction of the grain of the plate renders the plate useless.

The described treatment of the plates renders them impervious to the action of chromic, and like acids used in printing to keep the plates, clean, such acids having no undesirable-efiect upon the printing surfaces of the plates.

The foregoing method of treatment is particularly adapted for plates intended to produce fine work. For solids, such as lettering, broad lines, etc., where the character of the work is not required to be of an ex treme degree of fineness, I have found it advantageous to use, in lieu of the banana oil, a composition of fossil kaurigum,turpentine and Chinese oil to which is added a sufficient quantity of raw linseed oil to regulate the requirements as to drying, and a predetermined quantity of transparent printing ink, such as lacquer, to lend it color and give it a light body. The plate is laid aside until it becomes sticky or tacky, when it is immersed in water for a few minutes, the gum arabic, underneath the composition, free from grease, being dissolved. The surface of the plate is then brushed or rubbed,

and after being gummed, as before described,

hereinbefore described, equally good results being obtained.

I desire it to be understood that I do not confine myself to the use of banana oil, or the composition of fossil kaurigum, turpentine and (hinese oil, as these substances are only specimens of gums soluble in oil or turpentine, the equivalents of which I claim as my invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The process herein described of preparing metallic lithographic plates which consists in preparing and etching the plate in the usual manner, evenly coating the plate with a composition of fossil kaurigum, turpentine, and Chinese oil, and reetching the plate.

2. The process herein described of preparing metallic lithographic plates which consists in preparing and etching the plate in the usual manner, evenly coating the plate with solution of a gum in oil consisting of fossil 'kaurigum and Chinese oil, and turpentine, and rei tching the plate, testing the plate, again coating with a gum arabic solution, washing it with turpentine, coating with the gum solution in oil and turpentine and again etching the plate.

3. The process herein described for preparing lithographic plates which consists in pressing the impression paper on the plate, soaking the paper off, coating with a solution of gum arabic, rubbing ink upon the plate, dusting with talcum powder, etching with a solution of acid gum arabic, again coating with gum arabic solution, drying, washing the ink off with turpentine, coating with a solution of asphaltum in turpentine, testing the plate, and finally coating the plate evenly with a composition of fossil kaurigum, turpentine and Chinese oil, and again etching the plate.

In testimony whereof I affix my signature in presence of two Witnesses.

JOSEPH JAMES. Witnesses:

E. l/VALTON BREWINGTON, HOWARD D. ADAMS. 

